I am trying to publish a Double value from the command line, but it says it can't convert the value. It tried:

ign topic -t "/model/simple-robot/joint/the_joint/cmd_pos" -p "1.3" --msgtype ignition::msgs::Double
ign topic -t "/model/simple-robot/joint/the_joint/cmd_pos" -p "data: 1.3" --msgtype ignition::msgs::Double
ign topic -t "/model/simple-robot/joint/the_joint/cmd_pos" -p 1.3 --msgtype ignition::msgs::Double

But I get the message Unable to create message of type[ignition::msgs::Double] with ... with my value for p on the ...s. How can I send a double value? And is there an overview with the stucture of all the default ignition messages?